As a partial overlay method for partially decorating a large body to be coated such as a body of an automobile with a film, the following method is disclosed (Patent Document 1). In the method, an accommodating chamber having an upper portion thereof opened and an upper box having a lower portion thereof opened are vertically combined with a decorative film interposed therebetween to form a formed space in a sealed manner in which a box space and an accommodating space are vertically contiguously formed. Then, the decorative film is stuck through pressure reduction to a partial surface of the body to be coated W accommodated in the formed space by instantaneously generating a pressure difference between the upper and lower spaces in the formed space.
In addition, in a large body to be coated made of a formed plate material, a structure in which a back side of a formed surface is reinforced with a lower panel and a hollow structure is formed by an upper panel and the lower panel is often adopted. For example, as a front suspension member of an automobile, there is disclosed a hollow structure formed by an upper panel and a lower panel, and having a front arm attachment portion and a rear arm attachment portion on each lateral side portion (Patent Document 2). In the hollow structure, for example, a longitudinal wall extending substantially linearly from the front arm attachment portion to the rear arm attachment portion is provided. The rear arm attachment portion is formed of a portion obtained by extending the upper panel in the lateral direction, and a brace welded to the lower panel and projected in the lateral direction.